1. Field of the Invention
This invention relates in general to the construction of liquid fuel rocket engines and in particular to a new and useful apparatus and method for operating said engines to control the dimension of the nozzle throat section in accordance with the engine operation.
2. Description of the Prior Art
In the control of the thrust output of rocket engines it is known to keep the combustion chamber pressure constant by varying the cross-section of the throat in order to obtain better performance values than in normal combustion chamber pressure regulations where the specific impulse drops considerably at partial load, particularly in the vicinity of the ground and hence in the first stages of operation of missiles. Thus it is known to construct a ring throat nozzle with a narrow ring slot behind the nozzle throat at the inner boundary wall and the outer boundary wall is open outwardly so that the jet exit surface adapts itself automatically to the respective expansion ratio and the inner nozzle part is displaced axially during the control of the longitudinal thrust. It is also known to provide a bell shaped nozzle with a mushroom type insert body mounted for longitudinal and pivotal movement in the throat for controlling the longitudinal and transverse thrust. The axial and radial adjustment of such a device depends on the size and direction of the desired thrust vector as disclosed in U.S. Pat. No. 3,192,714. Both types of control of the throat cross-section require a complicated mechanism with a constructionally elaborate support and sealing for a moving part that is under high thermal stress and pressure.